The present invention generally relates to particulate compositions, and more particularly, to particulate compositions which have a plasma-induced, graft polymerized, water-soluble coating. The particulate compositions may be used in shampoos, skin care and other cosmetic products, deodorant products, laundry, dishwashing, carwashing and other similar applications. The plasma-induced, graft polymerized, water-soluble coating can control solubility, dispersion, flowability, enhance chemical stability or be a functional additive to the particulate composition. The invention also provides a process for making such plasma-induced, graft polymerized, coated particulate compositions.
Currently, formulators of various cosmetic, laundry, dishwashing, shampoo, and other particulate-containing compositions are faced with numerous problems which impede delivering the active ingredients and attaining the full benefit of all of the ingredients in such compositions. By way of example, recent low dosage or xe2x80x9ccompactxe2x80x9d detergent products experience dissolution problems, especially in cold temperature laundering solutions (i.e., less than about 30xc2x0 C.). More specifically, poor dissolution results in the formation of xe2x80x9cclumpsxe2x80x9d which appear as solid white masses remaining in the washing machine or on the laundered clothes after conventional washing cycles. These xe2x80x9cclumpsxe2x80x9d are especially prevalent under cold temperature washing conditions and/or when the order of addition to the washing machine is laundry detergent first, clothes second and water last (commonly known as the xe2x80x9cReverse Order Of Additionxe2x80x9d or xe2x80x9cROOAxe2x80x9d). Similarly, this clumping phenomenon can contribute to the incomplete dispensing of detergent in washing machines equipped with dispenser drawers or in other dispensing devices, such as a granulette. In this case, the undesired result is undissolved detergent residue in the dispensing device.
Another similar problem with detergent compositions, especially granular laundry and dishwashing detergents, is the degradation of physical properties over extended storage periods. More particularly, spray dried granules and other particulate detergent ingredients have a tendency to xe2x80x9ccakexe2x80x9d while stored in the detergent box, especially under highly humid conditions. Such xe2x80x9ccakingxe2x80x9d is very unacceptable to consumers and can lead to difficulties in xe2x80x9cscoopingxe2x80x9d or otherwise removing the detergent from the box in which it is contained. This problem can also result in improper dosing of the laundering solution resulting in decreased cleaning performance. Other problems include chemical instability of the detergent composition and difficulty in dispersing polymers into wash solutions. Heretofore, detergent formulators have unsuccessfully attempted to resolve or minimize all of the aforementioned problems, and they continue to search for convenient solutions which do not affect other properties of the detergent composition.
Accordingly, despite the above disclosures in the art, there is a need for compositions, and a process for making such compositions, which have improved physical properties, solubility and/or chemical stability.
The invention meets the above-identified needs by providing a composition having a plasma-induced, graft polymerized, water-soluble coating for controlling solubility, chemical stability and physical properties. The invention also provides a process for making such a composition involving subjecting a particulate material to a plasma glow zone to form free radicals onto the surface, after which an organic hydrophilic monomer is introduced such that it ultimately deposits on the particular material by graft polymerization to form a water soluble coating. The plasma glow zone is contained in a plasma chamber and operated at selected power and pressures so as not to destroy or otherwise alter the functionality or stability of the coating or the particulate material that is being coated.
In accordance with one aspect of the invention, a composition is provided. The composition comprises a particulate material having at least a portion which has a plasma-induced, graft polymerized, water-soluble coating, wherein the water-soluble coating is formed by ionizing gas in a plasma chamber to form free radicals on the portion of the particulate material after which an organic hydrophilic monomer is deposited onto the portion of the particulate material by graft polymerization so as to form the water-soluble coating on the portion of the particulate material.
In accordance with yet another aspect of the invention, a process for producing a water-soluble composition is provided. The process comprises the steps of: (a) providing a particulate material; (b) subjecting at least a portion of the particulate material to plasma glow zone in which a gas is ionized to form free radicals on the portion of the particulate material, wherein the plasma glow zone is contained in a plasma chamber operated at a pressure of from about 1 mTorr to about 300 Torr and a power of from about 0.1 Watts to about 500 Watts; (c) introducing a water-soluble, organic hydrophilic monomer into the chamber after the step (b) such that the organic hydrophilic monomer reacts with the free radicals on the portion of the particulate material so as to form a water-soluble coating on the portion of the particulate material.
As used herein, the xe2x80x9cplasma glow zonexe2x80x9d is the space or region where plasma is generated using electricity, such as the space between two electrodes in a plasma vacuum chamber. As used herein, the phrase xe2x80x9cplasma chamberxe2x80x9d or xe2x80x9cplasma vacuum chamberxe2x80x9d includes or can be embodied in fluidized beds, tumbling drums, vibrating belts and other similar apparatus. All percentages, ratios and proportions used herein are by weight, unless otherwise indicated. All documents including patents and publications cited herein are incorporated herein by reference.
Accordingly, it is an advantage of the invention to provide a composition which has improved physical properties, solubility and/or chemical stability. It is also an advantage of the invention to provide a process for producing such compositions in an convenient manner. These and other advantages and features of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of the preferred embodiments and the appended claims.